Photosensitivity isn't unheard of, I haven't run into any dogs with it but I wouldn't be at all surprised. I don't know how something like that could be dealt with, life would suck being allergic to the sun. I hope it just lack of pigment.

I've never heard of dogs being allergic to sun, but my step-sister is, so if it's possible with people, it's probably possible with dogs. And, to clarify, it's not that she burns fast in the sun (she tans nicely actually), she just gets a rash, which can even turn scabby .

Here's a weird one, I have a friend who's skin is sensitive/allergic to water. Seriously, you'd think it'd be impossible, or it was just the soap or something, but it's not. When her skin gets wet (shower, swimming, rain, whatever), even with pure H2O, she gets hives. They go away within a couple hours, but she just always is kind of itchy and gross poor girl.

I had a friend like that too! She developed the condition later in life (like 25-26 yrs old). She found out the scary way one day when she took a trip to the ocean. She was wading around and swimming when it first reared it's ugly head. Since she was completely immersed she had a very severe reaction and almost went into anaphylactic (sp?) shock. For her it's brought on by cold water. Warm or hot water is okay. Still sucks though for her. If she gets even one drop of cold water on her she gets nasty welts and hives.